Ultraschall und Arthritis

Zusammenfassung: Die Arthrosonographie ist ein etabliertes und validiertes diagnostisches Verfahren in der Rheumatologie. Durch ihren hohen Weichteilkontrast ist die Sonographie in der Lage, Weichteilveränderungen wie z.B. Synovialisveränderungen zu detektieren. Knorpel- oder Knochenveränderungen im Rahmen einer rheumatoiden Arthritis (RA), einer Spondyloarthritis oder einer Kristallarthritis können teilweise nur sonographisch oder in vielen Fällen zu einem früheren Zeitpunkt als mit der konventionellen Bildgebung erfasst werden. Die Aktivität entzündlicher Veränderungen kann mit Hilfe der Doppler- und Power-Dopplersonographie gut dargestellt werden. In der Früharthritisdiagnostik gewinnt die Sonographie zunehmend an Bedeutung, insbesondere bei undifferenzierter Arthritis und bei unauffälligem Röntgenbefund. Neben der Diagnostik der Früharthritis und dem Therapiemonitoring einer RA erlaubt die Sonographie die Darstellung pathognomonischer Veränderungen bei seronegativen Spondyloarthritiden und Kristallablagerungserkrankungen wie Gicht, Chondrokalzinose und Apatitose. Sonographiegesteuerte diagnostische und therapeutische Interventionen zeichnen sich durch eine extrem hohe Treffsicherheit und Verbesserung der klinischen Wirksamkeit verglichen mit ungesteuerten Verfahren aus. Zusammenfassend nimmt die Sonographie zunehmend einen zentralen Stellenwert ein in der Abklärung und Behandlungssteuerung bei entzündlichen Gelenkerkrankunge

Why High-Frequency Pulse Tubes Can Be Tipped

Presented at the 16th International Cryocooler Conference, held May 17-20, 2008 in Atlanta, Georgia.The typical low-frequency pulse-tube refrigerator loses significant cooling power when it is tipped with the pulse tube’s cold end above its hot end, because natural convection in the pulse tube loads the cold heat exchanger. Yet most high-frequency pulse-tube refrigerators work well in any orientation with respect to gravity. In such a refrigerator, natural convection is suppressed by sufficiently fast velocity oscillations, via a nonlinear hydrodynamic effect that tends to align the density gradients in the pulse tube parallel to the oscillation direction. Since gravity’s tendency to cause convection is only linear in the pulse tube’s end-to-end temperature difference while the oscillation’s tendency to align density gradients with oscillating velocity should be quadratic in that temperature difference, it is easiest to suppress convection when the end-to-end temperature difference is largest. Simple experiments demonstrate this temperature dependence, the strong dependence on the oscillating velocity, and little or no dependence on the magnitude or phase of the oscillating pressure. In some circumstances in this apparatus, the suppression of convection is a hysteretic function of oscillating velocity. In some other circumstances, a time-dependent convective state seems more difficult to suppres

Incorporating Freehand Sketches and Mockups into Senior Design Capstone Course: Case Study with a Hand Cycle Vehicle Rack

From the students’ perspective, the project objective of this 2-semester senior design course was to design and build a storage device for a hand powered upright hand cycle that can be installed on the exterior of a wheelchair accessible Dodge-Chrysler minivan so that a person with paraplegia or quadriplegia can drive the vehicle independently (without a human aide) when the hand cycle is loaded on the vehicle. The novelty of this paper is the pedagogy of blending traditional methods of engineering design (hand sketches, low resolution mockups, and prototypes) along with CAD design and modern computational analytics, including FEA, in a 2-semester design course. Students drew sketches of multiple ideas and made a full-size three dimensional mockup of the rear of a Chrysler minivan out of plywood and structural wood. They also made two mockups and two metal prototypes and analyzed the design with FEA. Course evaluations from students revealed their appreciation for having the opportunity to hand sketch ideas and make low resolution mockups in the first semester to arrive at a general design. (The second semester was devoted to detailed design and making functional prototypes.) The students felt that they had a rich design experience that they could use for future design projects in their careers

Educational recommendations for the conduct, content and format of EULAR musculoskeletal ultrasound Teaching the Teachers Courses

To produce educational guidelines for the conduct, content and format of theoretical and practical teaching at EULAR musculoskeletal ultrasound (MSUS) Teaching the Teachers (TTT) Courses

Josephson effects in dilute Bose-Einstein condensates

We propose an experiment that would demonstrate the ``dc'' and ``ac'' Josephson effects in two weakly linked Bose-Einstein condensates. We consider a time-dependent barrier, moving adiabatically across the trapping potential. The phase dynamics are governed by a ``driven-pendulum'' equation, as in current-driven superconducting Josephson junctions. At a critical velocity of the barrier (proportional to the critical tunneling current), there is a sharp transition between the ``dc'' and ``ac'' regimes. The signature is a sudden jump of a large fraction of the relative condensate population. Analytical predictions are compared with a full numerical solution of the time dependent Gross-Pitaevskii equation, in an experimentally realistic situation.Comment: 4 pages, 1 figur

Copepod carcasses in the subtropical convergence zone of the Sargasso Sea: implications for microbial community composition, system respiration and carbon flux

We showed that copepod carcasses were prevalent in the dynamic subtropical convergence zone where the water column stratification pattern can change considerably across the front as warm and cold water masses converge. The proportional numerical abundances of copepod carcasses increased with depth, reaching up to 91% at 300–400 m. On average 14–19% of the copepods in the upper 200 m were carcasses. Combining field and experimental data, we estimated that decomposing copepod carcasses were a negligible oxygen sink in the STCZ, but sinking carcasses represent an overlooked source of the passive carbon sinking flux in the area

Observatory's linguistic landscape: semiotic appropriation and the reinvention of space

Using a longitudinal ethnographic study of the linguistic landscape (LL) in Observatory's business corridor of Lower Main Road, the paper explores changes brought about by the influx of immigrant Africans, their artefacts and language practices. The paper uses the changes in the LL over time and the development of an "African Corner" within Lower Main Road, to illustrate the appropriation of space and the unpredictability, which comes along with highly mobile, technological and multicultural citizens. It is argued that changes in the LL are part of the act of claiming and appropriating space wherein space becomes summarily recontexualized and hence reinvented and "owned" by new actors. It is also argued that space ownership can be concealed through what we have called "brand anonymity" strategies in which the identity of the owner is deliberately concealed behind global brands. We conclude that space is pliable and mobile, and that, it is the people within space who carve out new social practices in their appropriated space.IBS

Characterization of irradiated RD53A pixel modules with passive CMOS sensors

We are investigating the feasibility of using CMOS foundries to fabricate silicon detectors, both for pixels and for large-area strip sensors. The availability of multi-layer routing will provide the freedom to optimize the sensor geometry and the performance, with biasing structures in poly-silicon layers and MIM-capacitors allowing for AC coupling. A prototyping production of strip test-structures and RD53A compatible pixel sensors was recently completed at LFoundry in a 150$\,$nm CMOS process. This paper will focus on the characterization of irradiated and non-irradiated pixel modules, composed by a CMOS passive sensor interconnected to a RD53A chip. The sensors are designed with a pixel cell of $25\times100\,\mu \mathrm{m}^2$ in case of DC coupled devices and $50\times50\,\mu \mathrm{m}^2$ for the AC coupled ones. Their performance in terms of charge collection, position resolution, and hit efficiency was studied with measurements performed in the laboratory and with beam tests. The RD53A modules with LFoundry silicon sensors were irradiated to fluences up to $1.0\times10^{16}\,\frac{\mathrm{n}_\mathrm{eq}}{\mathrm{cm}^2}$